package com.yuuzy.dao;

import com.yuuzy.utils.DBUtils;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.BeanHandler;
import org.apache.commons.dbutils.handlers.BeanListHandler;
import org.apache.commons.dbutils.handlers.ScalarHandler;

import javax.sql.DataSource;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.List;


public class BasicDAO<T> {
    private DataSource ds;
    //泛型指定具体的类型
    private QueryRunner qr = new QueryRunner(ds);

    public BasicDAO() {
    }

    //开发通用的dml方法，针对任意的表
    public int update(String sql, Object... parameters) {
        Connection connection = null;
        try {
            connection = DBUtils.getConnection();
            int update = qr.update(connection, sql, parameters);
            return update;
        } catch (SQLException e) {
            throw new RuntimeException(e);//将编译异常-->运行异常，抛出
        } finally {
            DBUtils.close(null, null, connection);
        }
    }
    //返回多个对象(即查询的结果是多行），针对任意表

    /**
     * @param sql        sql语句，可以有?
     * @param clazz      传入一个类Class对象，比如Fund.class
     * @param parameters 传入？具体的值，可以是多个
     * @return 根据T.class 返回对应的 ArrayList 集合
     */
    public List<T> queryMulti(String sql, Class<T> clazz, Object... parameters) {
        Connection connection = null;
        try {
            connection = DBUtils.getConnection();
            return qr.query(connection, sql, new BeanListHandler<>(clazz), parameters);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        } finally {
            DBUtils.close(null, null, connection);
        }
    }

    //查询单行结果的通用方法
    public T querySingle(String sql, Class<T> clazz, Object... parameters) {
        Connection connection = null;
        try {
            connection = DBUtils.getConnection();
            return qr.query(connection, sql, new BeanHandler<>(clazz), parameters);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        } finally {
            DBUtils.close(null, null, connection);
        }
    }

    //查询单行单列的方法，即返回单值的方法
    public Object queryScalar(String sql, Object... parameters) {
        Connection connection = null;
        try {
            connection = DBUtils.getConnection();
            return qr.query(connection, sql, new ScalarHandler(), parameters);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        } finally {
            DBUtils.close(null, null, connection);
        }
    }
}
